U.S. patent application number 14/094568 was filed with the patent office on 2014-06-26 for mems device with multiple electrodes and fabricating method thereof.
This patent application is currently assigned to INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. The applicant listed for this patent is INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE. Invention is credited to YU WEN HSU, CHAO TA HUANG, CHIN FU KUO, CHUN KAI MAO, CHIN HUNG WANG.
Application Number | 20140175572 14/094568 |
Document ID | / |
Family ID | 50973697 |
Filed Date | 2014-06-26 |
United States Patent
Application |
20140175572 |
Kind Code |
A1 |
HSU; YU WEN ; et
al. |
June 26, 2014 |
MEMS DEVICE WITH MULTIPLE ELECTRODES AND FABRICATING METHOD
THEREOF
Abstract
A MEMS device with a first electrode, a second electrode and a
third electrode is disclosed. These electrodes are disposed on a
substrate in such a manner that (1) a pointing direction of the
first electrode is in parallel with a normal direction of the
substrate, (2) a pointing direction of the third electrode is
perpendicular to the pointing direction of the first electrode, (3)
the second electrode includes a sensing portion and a stationary
portion, (4) the first electrode and the sensing portion are
configured to define a sensing capacitor, and (5) the third
electrode and the stationary portion are configured to define a
reference capacitor. This arrangement facilitates the MEMS device
such as a differential pressure sensor, differential barometer,
differential microphone and decoupling capacitor to be
miniaturized.
Inventors: |
HSU; YU WEN; (TAINAN CITY,
TW) ; KUO; CHIN FU; (TAINAN CITY, TW) ; HUANG;
CHAO TA; (HSINCHU CITY, TW) ; MAO; CHUN KAI;
(TAINAN CITY, TW) ; WANG; CHIN HUNG; (HSINCHU
CITY, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE |
HSINCHU |
|
TW |
|
|
Assignee: |
INDUSTRIAL TECHNOLOGY RESEARCH
INSTITUTE
HSINCHU
TW
|
Family ID: |
50973697 |
Appl. No.: |
14/094568 |
Filed: |
December 2, 2013 |
Current U.S.
Class: |
257/415 ;
438/50 |
Current CPC
Class: |
A61B 2562/028 20130101;
B81B 2201/0235 20130101; B81B 2201/0257 20130101; G01P 15/125
20130101; G01L 9/0073 20130101; G01P 2015/0837 20130101; B81B
2201/0242 20130101; G01P 15/0802 20130101; B81B 2201/0221 20130101;
B81B 3/0086 20130101; B81B 2201/0264 20130101 |
Class at
Publication: |
257/415 ;
438/50 |
International
Class: |
B81B 3/00 20060101
B81B003/00; B81C 1/00 20060101 B81C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2012 |
TW |
101148598 |
Mar 28, 2013 |
CN |
201310105428.8 |
Jun 4, 2013 |
TW |
102119719 |
Claims
1. A MEMS device with multiple electrodes, being adapted to sense
air pressure, comprising: a substrate; a first electrode on the
substrate; a second electrode on the substrate, including a sensing
portion and a stationary portion; and a third electrode on the
substrate, wherein when the sensing portion deforms, the stationary
portion and the third electrode are spaced apart by a predetermined
constant distance.
2. The MEMS device according to claim 1, wherein a stationary
capacitor is defined between the stationary portion and the third
electrode, and a sensing capacitor is defined between the sensing
portion and the first electrode.
3. The MEMS device according to claim 1, wherein the first
electrode is disposed on a top surface of the substrate, the
stationary portion surrounds the first electrode, and the third
electrode surrounds the second electrode.
4. The MEMS device according to claim 3, wherein one end of the
stationary portion is disposed on the top surface of the substrate
and the other end of the stationary portion connects a periphery of
the sensing portion, a first space is defined between the second
electrode and the substrate, and the first space is a hermetic
space, which encloses the first electrode.
5. The MEMS device according to claim 4, further comprising an
electrical insulation layer connecting the sensing portion and the
third electrode, wherein the electrical insulation layer, the
stationary portion, the third electrode and the substrate define a
second space which is a hermetic space.
6. The MEMS device according to claim 4, further comprising a
conductive post, wherein the stationary portion includes a through
hole, the conductive post is disposed inside the through hole and
is electrically coupled to the first electrode, and the conductive
post is electrically insulated from the stationary portion.
7. The MEMS device according to claim 6, wherein the electrical
insulation layer includes a first conductive through hole and a
second conductive through hole, the first conductive through hole
connects with the conductive post, and the second conductive
through hole is electrically coupled to the second electrode.
8. A MEMS device with multiple electrodes, being adapted to sense
air pressure, comprising: a substrate; a first electrode on the
substrate; a second electrode configured to define a sensing
capacitor between the first electrode and the second electrode; and
a third electrode on the substrate, configured to define a
stationary capacitor; wherein the third electrode disconnects from
the second electrode or the third electrode disconnects from the
first electrode, a pointing direction of the first electrode is in
parallel with a normal direction of the substrate, a pointing
direction of the third electrode is perpendicular to the pointing
direction of the first electrode.
9. The MEMS device according to claim 8, wherein the second
electrode further includes a sensing portion, a deforming direction
of the sensing portion is in parallel with the normal direction of
the substrate.
10. The MEMS device according to claim 8, wherein the first
electrode is disposed on a top surface of the substrate, the second
electrode includes a sensing portion and a stationary portion, the
stationary portion surrounds the first electrode, and the third
electrode surrounds the stationary portion.
11. The MEMS device according to claim 10, wherein one end of the
stationary portion is disposed on the top surface of the substrate
and the other end of the stationary portion connects a periphery of
the sensing portion, a first space is defined between the second
electrode and the substrate, the first space is a hermetic space
which encloses the first electrode.
12. The MEMS device according to claim 11, further comprising an
electrical insulation layer connecting the sensing portion and the
third electrode, wherein the electrical insulation layer, the
stationary portion, the third electrode and the substrate define a
second space which is a hermetic space.
13. The MEMS device according to claim 11, further comprising a
conductive post, wherein the stationary portion includes a through
hole, the conductive post is disposed inside the through hole and
is electrically coupled to the first electrode, and the conductive
post is electrically insulated from the stationary portion.
14. The MEMS device according to claim 13, wherein the electrical
insulation layer includes a first conductive through hole and a
second conductive through hole, the first conductive through hole
connects with the conductive post, and the second conductive
through hole is electrically coupled to the second electrode.
15. A MEMS device with multiple electrodes, comprising: a
substrate; a first electrode on the substrate, wherein a pointing
direction of the first electrode is in parallel with the normal
direction of the substrate; a second electrode on the substrate,
including a sensing portion and a stationary portion; and a third
electrode on the substrate, wherein a pointing direction of the
third electrode is perpendicular to the pointing direction of the
first electrode; wherein the sensing portion faces the first
electrode, the stationary portion faces the third electrode, when
the sensing portion deforms, the stationary portion and the third
electrodes are spaced apart by a predetermined constant
distance.
16. The MEMS device according to claim 15, wherein a deforming
direction of the sensing portion is in parallel with the normal
direction of the substrate.
17. The MEMS device according to claim 15, wherein the first
electrode is disposed on a top surface of the substrate, the
stationary portion surrounds the first electrode, the third
electrode surrounds the stationary portion, the sensing portion and
the first electrode are spaced apart by a gap.
18. The MEMS device according to claim 17, wherein the stationary
portion includes a plurality of first protruding portions, and the
third electrode includes a plurality of second protruding portions,
wherein the first protruding portions and the second protruding
portions are arranged to form an interdigital capacitor.
19. The MEMS device according to claim 17, wherein one end of the
stationary portion is disposed on the top surface of the substrate
and the other end of the stationary portion connects the sensing
portion.
20. The MEMS device according to claim 19, wherein the sensing
portion, the stationary portion and the substrate define a first
space which encloses the first electrode.
21. The MEMS device according to claim 20, wherein the first space
is a hermetic space.
22. The MEMS device according to claim 20, further comprising an
electrical insulation layer connecting the second electrode and the
third electrode, wherein the electrical insulation layer, the
stationary portion, the third electrode and the substrate define a
second space.
23. The MEMS device according to claim 22, wherein the second space
is a hermetic space.
24. The MEMS device according to claim 19, further comprising a
conductive post, wherein the stationary portion includes a through
hole, the conductive post is disposed inside the through hole and
is electrically coupled to the first electrode, and the conductive
post is electrically insulated from the stationary portion.
25. The MEMS device according to claim 19, further comprising an
electrical insulation layer connecting the second electrode and the
third electrode, wherein the electrical insulation layer, the
stationary portion, the third electrode and the substrate define a
second space, and the electrical insulation layer covers the
partial sensing portion.
26. The MEMS device according to claim 22, further comprising a
first conductive layer disposed on the electrical insulation
layer.
27. The MEMS device according to claim 25, further comprising a
second conductive layer disposed on the sensing portion which is
not covered by the electrical insulation layer.
28. The MEMS device according to claim 24, further comprising an
integrated circuit chip, wherein the material of the substrate is
made of glass, the integrated circuit chip is disposed on a bottom
surface of the substrate, and the integrated circuit chip is
electrically coupled to the conductive post.
29. The MEMS device according to claim 24, further comprising a
first conductive post, an external conductive trace, an electrical
isolation layer, a conductive trace layer, a conductive bump, and a
conductive trace, wherein, the first conductive post is disposed
inside the third electrode, the first conductive post is
electrically insulated from the third electrode, the electrical
insulation layer includes a first conductive through hole and a
second conductive through hole, the external conductive trace is
disposed on the electrical insulation layer, the electrical
isolation layer is disposed on a bottom surface of the third
electrode, the electrical isolation layer includes a third
conductive through hole, the conductive trace layer is disposed
below the electrical isolation layer, the partial conductive trace
layer is disposed between the electrical isolation layer and the
substrate, the conductive bump is disposed on the integrated
circuit chip, the first conductive through hole of the electrical
insulation layer connects the conductive post to the external
conductive trace, the second conductive through hole of the
electrical insulation layer connects the external conductive trace
to the first conductive post, the third conductive through hole of
the electrical isolation layer connects the first conductive post
to the conductive trace layer, and the conductive wire connects the
conductive trace layer and the conductive bump.
30. The MEMS device according to claim 24, wherein the electrical
insulation layer includes a first conductive through hole and a
second conductive through hole, the first conductive through hole
connects with the conductive post, and the second conductive
through hole is electrically coupled to the second electrode.
31. The MEMS device according to claim 24, wherein the substrate is
an integrated circuit chip further including at least one
conductive through hole, wherein the at least one conductive
through hole is configured to allow the first electrode, the second
electrode and the third electrode to be electrically coupled to at
least one conductive bump of the integrated circuit chip,
respectively.
32. The MEMS device according to claim 31, further comprising a
second conductive post, wherein a conductive layer is disposed on
the electrical insulation layer, the second conductive post is
disposed inside the third electrode and is electrically insulated
from the third electrode, and the at least one conductive through
hole is electrically coupled to the conductive layer through the
conductive post.
33. The MEMS device according to claim 22, wherein the substrate
includes at least one opening and a back chamber, wherein the at
least one opening communicates with the second space, the back
chamber is disposed under the first electrode, and the first
electrode further includes a plurality of apertures by which the
back chamber communicates with the first space.
34. The MEMS device according to claim 20, further comprising a
dielectric material which is disposed in the first space and is
disposed between the stationary portion and the third
electrode.
35. A fabricating method of a MEMS device with multiple electrodes,
the method comprising the following steps: providing a Silicon On
Insulator (SOI) wafer, wherein the SOI wafer includes a device
layer, an electrical insulation layer and a handle layer, wherein
the electrical insulation layer is disposed between the device
layer and the handle layer; etching the device layer to form a
recession; etching the device layer having the recession to form a
plurality of slots which expose the electrical insulation layer and
to form a through hole which exposes the electrical insulation
layer, wherein the slots and the recession define the second
electrode which includes a sensing portion and a stationary
portion, the through hole is disposed in the stationary portion,
the slots also define the third electrode and a conductive post
which is disposed inside the through hole and is electrically
insulated from the stationary portion; to providing a substrate
wafer on which a first electrode is disposed; bonding the SOI wafer
and the substrate wafer through wafer-to-wafer bonding to allow the
second electrode and the third electrode to connect to a top
surface of the substrate wafer, wherein the sensing portion faces
the first electrode, the stationary portion faces the third
electrode, and a pointing direction of the third electrode is
perpendicular to a pointing direction of the first electrode; and
removing the handle layer.
36. The fabricating method according to claim 35, wherein the slots
are configured for the stationary portion to form a plurality of
first protruding portions and are configured for the third
electrode to form a plurality of second protruding portions, and
the first protruding portions and the second protruding portions
are arranged to form an interdigital capacitor.
37. The fabricating method according to claim 35, wherein one end
of the stationary portion is disposed on the top surface of the
substrate and the other end of the stationary portion connects a
periphery of the sensing portion, the second electrode is
configured to seal the first electrode, the sensing portion, the
stationary portion, the electrical insulation layer and the
substrate define a first space, and the first space is a hermetic
space.
38. The fabricating method according to claim 35, wherein the
electrical insulation layer covers the second electrode and the
third electrode, the electrical insulation layer, the stationary
portion, the third electrode and the substrate define a second
space, and the second space is a hermetic space.
39. The fabricating method according to claim 35, further
comprising one of the following steps or a combination thereof:
etching the electrical insulation layer to form at least one
opening; depositing a first conductive layer on the electrical
insulation layer; and depositing a deposited conductive layer on
the first conductive layer to form at least one electrical contact.
Description
[0001] The present application claims priority from Taiwanese
application Ser. No. 101148598, filed on Dec. 20, 2012, and Ser.
No. 102119719, filed on Jun. 4, 2013, of the same title and
inventorship herewith and from Chinese application Ser. No.
201310105428.8, filed on Mar. 28, 2013, of the same title and
inventorship herewith.
1. TECHNICAL FIELD
[0002] The present disclosure relates to a MEMS device and a
fabricating method thereof, and more particularly, to a
multiple-electrode MEMS device having a first capacitor and a
second capacitor, and a fabricating method thereof.
2. BACKGROUND
[0003] Pressure sensors may be embedded into various mobile devices
such as cell-phones, laptops, tablet computers, and vehicle
navigation systems. Mobile devices with the pressure sensors are
capable of performing 3-dimension navigation. In the future,
applications of 3-dimension navigation may include indoor
navigation, and outdoor navigation for tunnel, bridge and overpass.
Thus, the navigation system requires an update from Global
Positioning System (GPS) with 9-axis inertial sensors (including an
accelerometer, a gyroscope and a magnetometer) to GPS with 10-axis
inertial navigator (including an accelerometer, a gyroscope, a
magnetometer and an air pressure sensor (also called a
"barometer").
[0004] Generally, the higher the altitude, the lower the air
pressure. The barometer (one kind of pressure sensor) is used to
detect the change in air pressure so as to evaluate the change in
altitude. A conventional air pressure sensor 1 shown in FIG. 1
includes a substrate 2, a stationary electrode 3 and a cover 4. The
cover 4 is disposed on the substrate 2 and shelters the stationary
electrode 3. In addition, the cover 4 includes a diaphragm 4-1. A
hermetic space 5 is defined between the diaphragm 4-1 and the
stationary electrode 3.
[0005] The conventional air-pressure sensor 1 includes two types of
sensors. One type of the air-pressure sensors is utilized to detect
absolute pressure while the other type of the air-pressure sensors
is used to measure relative pressure. For detecting the absolute
pressure, the hermetic space 5 of the former sensor is vacuum. When
such a sensor is placed in an environment where an external air
pressure P exists relative to the cover 4, the diaphragm 4-1 will
deform. The deformation will change the capacitance between the
diaphragm 4-1 and the stationary electrode 3 due to a change in the
distance therebetween. In accordance with the change in
capacitance, a processor may calculate an air-pressure value. Thus,
the air-pressure value is an absolute pressure value of the
external air-pressure P.
[0006] Regarding the sensor for measuring relative pressure, there
is a gas-pressure P.sub.1 in the hermetic space 5. As shown in FIG.
2, in a certain altitude, when the external air-pressure maintains
at P.sub.2, the diaphragm 4-2 will produce deformation d.sub.1. The
deformation will change the capacitance between the diaphragm 4-2
and the stationary electrode 3-1 due to a change in the distance
therebetween. In accordance with the change in capacitance, a
processor may calculate an air-pressure value. Thus, the
air-pressure value is a relative pressure value between the
external air-pressures P.sub.1 and P.sub.2. Either the sensors for
absolute pressure or the sensors for relative pressure are capable
of calculating the change of altitude according to the
above-mentioned pressure values, but in those sensors only a single
capacitor is provided, which is liable to error in pressure
measurement due to undesirable noise of the single capacitor.
[0007] In order to improve the conventional pressure sensors, as
shown in FIG. 3, a differential pressure sensor 6 is designed with
a sensing capacitor 7 including a movable electrode 7-1 and a
stationary electrode 7-2, and with a reference capacitor 8
including two stationary electrodes 8-1 and 8-2. The differential
pressure sensor 6 is capable of calculating the differential
capacitance between the sensing capacitor 7 and the reference
capacitor 8 so as to reduce noise.
[0008] FIG. 4 is a top view of the differential pressure sensor 6.
As shown in FIG. 4, a reference capacitor 8 of the differential
pressure sensor 6 increases the entire area of the differential
pressure sensor 6. Thus, it is difficult for the differential
pressure sensor 6 to use in a mobile device. FIG. 3 illustrates a
cross-sectional view of the differential pressure sensor 6, taken
from the line 1-1 in FIG. 4.
[0009] A differential pressure sensor 9 shown in FIG. 5 includes a
first electrode 9-1, a second electrode 9-2 and a third electrode
9-3. The first electrode 9-1 and the third electrode 9-3 form a
reference capacitor while the first electrode 9-1 and the second
electrode 9-2 form a sensing capacitor. When an external pressure
causes the first electrode 9-1 to deform, the distance between the
first electrode 9-1 and the third electrode 9-3 is changed and the
capacitance of a stationary electrode is affected. Consequently, an
error results in the calculation based on the capacitance
difference between the sensing capacitor and the reference
capacitor.
SUMMARY
[0010] The present disclosure provides a MEMS device with multiple
electrodes. The MEMS device includes a sensing capacitor and a
reference capacitor. The second electrode of the MEMS device
includes two portions. One portion is sensing portion, which is
configured for forming the sensing capacitor, while the other
portion is the stationary portion, which is configured for forming
the reference capacitor. In other words, one electrode of the
sensing capacitor and one electrode of the reference capacitor both
are located at the second electrode having the same electric
potential.
[0011] The present disclosure provides a MEMS device having
multiple vertical electrodes. The MEMS device includes a substrate,
a first electrode, a second electrode and a third electrode.
[0012] The first electrode, the second electrode and the third
electrode are disposed on the substrate. The second electrode
includes a sensing portion and a stationary portion. A variable
capacitor may be defined between the sensing portion of the second
electrode and the first electrode. The variable capacitor may be
also called a sensing capacitor in the present disclosure. A
stationary capacitor may be defined between the stationary portion
of the second electrode and the third electrode. The stationary
capacitor may be also called a reference capacitor in the present
disclosure.
[0013] When the second electrode deforms due to the external
pressure such as air pressure, the stationary portion and the third
electrode are spaced apart by a predetermined constant distance. In
other words, when sensing portion of the second electrode deforms,
the distance between the stationary portion and the third electrode
is constant as expected.
[0014] The present disclosure also provides another MEMS device
with multiple electrodes including a substrate, a first electrode,
a second electrode and a third electrode.
[0015] The first electrode and the third electrode are disposed on
the substrate. The first electrode and the second electrode are
configured to form a sensing capacitor. The third electrode is
configured to form a stationary capacitor (also called the
reference capacitor). The third electrode does not electrically
connect with the second electrode or the third electrode
disconnects from the first electrode.
[0016] The included angle between the pointing direction of the
first electrode and the pointing direction of the second electrode
is substantially 90.degree..
[0017] Moreover, the present disclosure also provides a MEMS device
which includes a substrate, a first electrode, a second electrode
and a third electrode.
[0018] The first electrode is disposed on the substrate. The
pointing direction of the first electrode is in parallel with the
normal direction of the substrate. The second electrode is disposed
on the substrate and the second electrode includes a sensing
portion and a stationary portion. The sensing portion faces the
first electrode.
[0019] The third electrode is disposed on the substrate. The
stationary portion faces the third electrode while the pointing
direction of the third electrode is perpendicular to the pointing
direction of the first electrode. The sensing portion faces the
first electrode. The stationary portion faces the third electrode.
When the sensing portion deforms, the stationary portion and the
third electrodes are spaced apart by a predetermined constant
distance.
[0020] The present disclosure also provide a fabricating method of
a MEMS device. The fabricating method includes the following
steps.
[0021] Silicon On Insulator (SOI) wafer is provided. The SOI wafer
includes a device layer, an electrical insulation layer and a
handle layer. The electrical insulation layer is disposed between
the device layer and the handle layer.
[0022] The device layer is etched to form a recession and a
plurality of slots exposing the electrical insulation layer. The
slots and the recession define a second electrode and a third
electrode in the device layer. In addition, the second electrode
includes a sensing portion and a stationary portion.
[0023] The stationary portion is etched to form a conductive post
and a through hole exposing the electrical insulation layer. A
conductive post is disposed inside the through hole while the
conductive post is electrically insulated from the stationary
portion.
[0024] A substrate wafer is provided and then a first electrode is
disposed on the substrate wafer.
[0025] The substrate wafer and the SOI wafer are bonded through
wafer-to-wafer bonding process. The second electrode and the third
electrode are connected to a top surface of the substrate wafer.
The sensing portion faces the first electrode. The stationary
portion faces the third electrode. The pointing direction of the
third electrode is perpendicular to the pointing direction of the
first electrode.
[0026] Finally, the handle layer is removed.
[0027] Another function of the present disclosure will be described
at following paragraphs. Certain functions can be realized in
present section, while the other functions can be realized in
detailed description. In addition, the indicated components and the
assembly can be explained and achieved by detail of the present
disclosure. Notably, the previous explanation and the following
description are demonstrated instead of limiting the scope of the
present disclosure.
[0028] The foregoing has outlined rather broadly the features and
technical benefits of the disclosure in order that the detailed
description of the disclosure that follows may be better
understood. Additional features and benefits of the disclosure will
be described hereinafter, and form the subject of the claims of the
disclosure. It should be appreciated by those skilled in the art
that the conception and specific embodiment disclosed may be
readily utilized as a basis for modifying or designing other
structures or processes for carrying out the same purposes of the
disclosure. It should also be realized by those skilled in the art
that such equivalent constructions do not depart from the spirit
and scope of the disclosure as set forth in the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the disclosure and, together with the description, serve to explain
the principles of the invention.
[0030] The foregoing summary, as well as the following detailed
description of the invention, will be better understood when read
in conjunction with the appended drawings. For the purpose of
illustrating the invention, there are shown in the drawings
examples which are presently preferred. It should be understood,
however, that the invention is not limited to the precise
arrangements and instrumentalities shown.
[0031] A more complete understanding of the present disclosure may
be derived by referring to the detailed description and claims when
considered in connection with the Figures, where like reference
numbers refer to similar elements throughout the Figures, and:
[0032] FIG. 1 is a cross-sectional view of a conventional
air-pressure sensor;
[0033] FIG. 2 is a cross-sectional view illustrating a conventional
air-pressure sensor pushed by an external air pressure P.sub.2;
[0034] FIG. 3 is a cross-sectional view of a conventional
differential pressure sensor;
[0035] FIG. 4 is a top view of the conventional differential
pressure sensor illustrated in FIG. 3;
[0036] FIG. 5 is a cross-sectional view of an upper portion and a
bottom portion of another conventional differential pressure
sensor;
[0037] FIG. 6 is a cross-sectional view of a MEMS device with
multiple electrodes in accordance with one embodiment of the
present disclosure;
[0038] FIG. 7 is a cross-sectional view of a MEMS device with
multiple electrodes in accordance with another embodiment of the
present disclosure;
[0039] FIG. 8 is a top view of a MEMS device in accordance with
another embodiment of the present disclosure;
[0040] FIG. 9 is a cross-sectional view of the MEMS device taken
along the line A-A' in FIG. 8 in accordance with an embodiment of
the present disclosure;
[0041] FIG. 10 is a cross-sectional view of the MEMS device taken
along the line B-B' in FIG. 9 in accordance with an embodiment of
the present disclosure;
[0042] FIG. 11 is a cross-sectional view of the MEMS device taken
along the line C-C' in FIG. 9 in accordance with an embodiment of
the present disclosure;
[0043] FIG. 12 is a cross-sectional view of the MEMS device taken
along the line D-D' in FIG. 8 embodiment of the present
disclosure;
[0044] FIG. 13 is a cross-sectional view of a modified MEMS device
derived from FIG. 8 taken along the line F-F' in accordance with an
embodiment of the present disclosure;
[0045] FIG. 14 is a cross-sectional view of a modified MEMS device
derived from FIG. 13 taken along the line G-G' in accordance with
an embodiment of the present disclosure;
[0046] FIG. 15 is a top view of a MEMS device in accordance with
another embodiment of the present disclosure;
[0047] FIG. 16 is a cross-sectional view of the MEMS device taken
along the line E-E in FIG. 15 in accordance with an embodiment of
the present disclosure;
[0048] FIG. 17 is a top view of a MEMS device in accordance with
another embodiment of the present disclosure;
[0049] FIG. 18 is a cross-sectional view of the MEMS device taken
along the line H-H' in FIG. 17 in accordance with an embodiment of
the present disclosure;
[0050] FIG. 19 is a cross-sectional view of the MEMS device taken
along the line J-J' in FIG. 19 in accordance with an embodiment of
the present disclosure;
[0051] FIG. 20 is a cross-sectional view of the MEMS device taken
along the line K-K in FIG. 20 in accordance with an embodiment of
the present disclosure;
[0052] FIG. 21 is a cross-sectional view of the MEMS device taken
along the line L-L' in FIG. 21 in accordance with an embodiment of
the present disclosure;
[0053] FIG. 22 is a cross-sectional view of the MEMS device taken
along the line I-I' in FIG. 22 in accordance with an embodiment of
the present disclosure;
[0054] FIG. 23 illustrates a top view and a cross-sectional view of
the MEMS device taken along the line M-M' in FIG. 23 in accordance
with another embodiment of the present disclosure;
[0055] FIG. 24 illustrates a top view and a cross-sectional view of
the MEMS device taken along the line N-N' in FIG. 24 in accordance
with another embodiment of the present disclosure;
[0056] FIG. 25 illustrates a top view and a cross-sectional view of
the MEMS device taken along the line O-O' in FIG. 25 in accordance
with another embodiment of the present disclosure;
[0057] FIG. 26 illustrates a top view and a cross-sectional view
taken along the MEMS device applied for silicon interposer in
accordance with another embodiment of the present disclosure;
[0058] FIG. 27 illustrates a top view and a cross-sectional view of
a modified MEMS device derived from FIG. 26 in accordance with an
embodiment of the present disclosure;
[0059] FIG. 28 is a flow chart of a fabricating method of a MEMS
device in accordance with an embodiment of the present disclosure;
and
[0060] FIGS. 29 to 37 are schematic views illustrating a method of
fabricating a MEMS device in accordance with one embodiment of the
present disclosure.
DETAILED DESCRIPTION
[0061] The present disclosure is directed to a MEMS device with
multiple electrodes and a fabricating method thereof. In order to
make the present disclosure completely comprehensible, detailed
steps and structures are provided in the following description.
Obviously, implementation of the present disclosure does not limit
special details known by persons skilled in the art. In addition,
known structures and steps are not described in details, so as not
to limit the present disclosure unnecessarily. Preferred
embodiments of the present disclosure will be described below in
detail. However, in addition to the detailed description, the
present disclosure may also be widely implemented in other
embodiments. The scope of the present disclosure is not limited to
the detailed embodiments, and is defined by the claims. The
following description of the disclosure accompanies drawings, which
are incorporated in and constitute a part of this specification,
and illustrate embodiments of the disclosure, but the disclosure is
not limited to the embodiments.
[0062] In addition, the following embodiments can be properly
integrated to complete another embodiment. References to "modified
embodiment," "the embodiment," "other embodiments," "another
embodiment," etc. indicate that the embodiment(s) of the disclosure
so described may include a particular feature, structure, or
characteristic, but not every embodiment necessarily includes the
particular feature, structure, or characteristic. Further, repeated
use of the phrase "in the embodiment" does not necessarily refer to
the same embodiment, although it may.
[0063] In addition, unless specifically stated otherwise, as
apparent from claims and detailed description, it is appreciated
that throughout the specification the quantity of components is
single. If the quantity of the labeled component is one, the
quantifier is explained to include one unit or at least one unit.
If the quantity of the labeled component is a plurality, the
quantifier is explained to include at least two units.
[0064] The following description of the disclosure accompanies
drawings, which are incorporated in and constitute a part of this
specification, and illustrate embodiments of the disclosure, but
are not limited to the embodiments. In addition, the following
embodiments can be properly integrated to complete another
embodiment.
[0065] FIG. 6 is a cross-sectional view of a MEMS device 10 with
multiple electrodes in accordance with one embodiment of the
present disclosure. In the embodiment shown in FIG. 6, the MEMS
device 10 with multiple electrodes includes a substrate 11, a first
electrode 12, a second electrode 13 and a third electrode 14.
[0066] In the present embodiment, the first electrode 12 is a
circular plate. However, in other embodiments (not shown), the
first electrode 12 may be designed with other geometric shapes
corresponding to the shape of the second electrode 13. As shown in
FIG. 6, the first electrode 12 is disposed on a top surface 111 of
the substrate 11. When the MEMS device 10 with multiple electrodes
measures the air pressure, the substrate 11 does not deform. Thus,
the first electrode 12 disposed on the substrate 11 may be regarded
as a stationary electrode used for sensing the air pressure.
[0067] In the present embodiment, the second electrode 13 is a
circular cover. However, in other embodiments (not shown), the
second electrode 13 may be designed with other geometric shapes,
such as square cover, corresponding to the shape of the third
electrode 14. As shown in FIG. 6, the second electrode 13 is
disposed on the substrate 11. In the specification and the
contemplated scope of protection, the term "on" means that a first
member is directly or indirectly disposed above the second member.
For instance, in the embodiment that the second electrode 13 is
disposed on the substrate 11, the second electrode 13 in one
example is directly disposed on the substrate 11, and in another
example is indirectly disposed above the substrate 11. The term
"indirectly" means that in a vertical view, two members are
disposed at an upper position and a lower position, respectively,
while other objects, material layers or gaps are disposed between
the two members.
[0068] The second electrode 13 includes a sensing portion 131 and a
stationary portion 132. When the MEMS device 10 with multiple
electrodes detects air pressure, the sensing portion 131 deforms.
Thus, the sensing portion 131 of the second electrode 13 and the
first electrode 12 define a variable capacitor which may be also
called a sensing capacitor.
[0069] In the present embodiment, the stationary portion 132 is a
ring structure. However, in other embodiments (not shown), the
shape of the stationary portion 132 may be designed with other
geometric shapes corresponding to the shape of the third electrode
14 or the first electrode 12. As shown in FIG. 6, the stationary
portion 132 is disposed on the top surface 111 while the stationary
portion 132 connects the sensing portion 131. Accordingly, the
stationary portion 132 is configured to separate the first
electrode 12 and the sensing portion 131 and form a gap.
Furthermore, one end of the stationary portion 132 is disposed on
the top surface 111 of the substrate 11 and the other end of the
stationary portion 132 connects with the periphery of the sensing
portion 131.
[0070] The third electrode 14 is disposed on the top surface 111 of
the substrate 11. In the embodiment, the third electrode 14 may be
shaped into a ring. However, in other embodiment (not shown), the
shape of the third electrode 14 may designed as other geometric
shapes, such as square ring, corresponding to the shape of the
third electrode 14 or the first electrode 12.
[0071] When the MEMS device 10 with multiple electrodes measures
air pressure, the stationary portion 132 and the third electrode 14
do not deform. Thus, the stationary portion 132 and the third
electrode 14 are spaced apart by a predetermined constant distance
d.sub.2. In other words, when the sensing portion 131 of the second
electrode 13 deforms, the predetermined constant distance d.sub.2
between the stationary portion 132 and the third electrode 14 still
maintains as a constant. In addition, the stationary portion 132
and the third electrode 14 define a reference capacitor. Since the
distance between the stationary portion 132 and the third electrode
14 is constant, the reference capacitor is also called a stationary
capacitor.
[0072] Since the second electrode 13 has same electrical voltage,
the voltage potential of the stationary portion 132 is identical to
the voltage potential of the sensing portion 131. The sensing
portion 131 and the first electrode 12 may form the sensing
capacitor. The stationary portion 132 and the third electrode 14
may form the reference capacitor.
[0073] The stationary portion 132 surrounds the first electrode 12
while the third electrode 14 surrounds the second electrode 13.
Since the sensing capacitor defined between the first electrode 12
and the sensing portion 131 and the reference capacitor defined
between the stationary portion 132 and the third electrode 14 are
disposed in an area which is surrounded by the third electrode 14,
it is possible for the MEMS device 10 with multiple electrodes to
be shrunk so as to meet the requirement of miniaturization of the
mobile electronics.
[0074] The second electrode 13 is configured to seal the first
electrode 12. In other words, after the second electrode 13
connects with the substrate 11, the second electrode 13 and the
substrate 11 will define a first space 15 where the first electrode
12 is disposed. In the embodiment, the first space 15 is a hermetic
space, which encloses the first electrode. However, in other
embodiments (not shown), the first space 15 is not limited to the
hermetic space and the first space 15 can be non-hermetic for
different designs.
[0075] In the specification and the scope of protection, the term
"hermetic space" may be defined as follows. Under the method
(MIL-STD-883E method 1014.9) of detecting gas density, after the
sample device with the first space is placed at a chamber filled
with helium gas (75.+-.2 psia) for two hours, the sample device is
located at a vacuum situation and is detected to calculate the
ratio of leaking helium gas. If the leaking ratio is less than the
standard (5.times.10.sup.-8 atm cc/sec), the first space in the
sample device can be termed as a hermetic space.
[0076] FIG. 7 is a cross-sectional view of a MEMS device 20 with
multiple electrodes in accordance with another embodiment of the
present disclosure. In the embodiment shown in FIG. 7, the MEMS
device 20 with multiple electrodes includes a substrate 21, a first
electrode 22, a second electrode 23 and a third electrode 24.
[0077] The first electrode 22 is disposed on the substrate 21. The
second electrode 23 and the first electrode 22 are configured to
define a sensing capacitor C.sub.1. Since the first electrode 22
faces the sensing portion 231 of the second electrode 23, the
pointing direction N.sub.1 of the first electrode 11 is in parallel
with the normal direction N of the substrate 21.
[0078] The second electrode 23 includes a sensing portion 231 and a
stationary portion 232. The third electrode 24 is disposed on the
substrate 21 and configured to form a reference capacitor C.sub.2,
which is also called a stationary capacitor. Moreover, the
stationary portion 232 of the second electrode 23 faces the third
electrode 24. The pointing direction N.sub.1 of the first electrode
22 is perpendicular to the pointing direction N.sub.2 of the third
electrode 24. However, in some embodiments, the fabricating process
for the MEMS device may cause error or tolerance which affects the
right angle between the pointing direction of the first electrode
22 and the pointing direction of the third electrode 24 so that the
angle between these two directions ranges from 89.degree. to
91.degree.. In the embodiment shown in FIG. 7, the MEMS device 20
with multiple electrodes further includes an electrical insulation
layer 25 which covers the second electrode 23 and the third
electrode 24. In the embodiment, the electrical insulation layer 25
may be, but not limited to, a circular plate. However, in other
embodiments (not shown), the electrical insulation layer 25 may be
designed with other shapes, such as a square. As shown in FIG. 7,
the electrical insulation layer 25 connects the sensing portion 231
of the second electrode 23 and the third electrode 24. In other
words, the electrical insulation layer 25 does not directly connect
with the first electrode 22. In addition, the sensing portion 231
of the sensing capacitor C.sub.1 and the stationary portion 232 of
the reference capacitor C.sub.2 both are located at the second
electrode 23 having the same electric potential.
[0079] The electrical insulation layer 25, the stationary portion
232, the third electrode 24 and the top surface 211 of the
substrate 21 define a second space 26. In the embodiment, the
second space 26 is a hermetic space. However, in other embodiments
(not shown), the second space 26 may be a non-hermetic space. For
example, the second space 26 may be filled with dielectric
material.
[0080] The stationary portion 232 includes a through hole 233. The
MEMS device 20 with multiple electrodes further includes a
conductive post 27, which is disposed inside the through hole 233
and is electrically coupled to the first electrode 22. Moreover,
the first electrode 22 further includes an extension terminal 221,
which is electrically coupled to the conductive post 27. Thus, the
voltage potential of the conductive post 27 is identical with the
voltage potential of the first electrode 22.
[0081] Furthermore, the stationary portion 232 and the conductive
post 27 are electrically conductive material. In order to avoid
electric short between the sensing portion 231 of the second
electrode 23 and the first electrode 22, the conductive post 27 and
the stationary portion 232 are spaced apart by a gap. As a result,
the conductive post 27 is electrically insulated from the
stationary portion 232. Furthermore, the sensing portion 231
further includes a hole 235 connecting the through hole 233. The
hole 235 is configured to accommodate the conductive post 27.
Accordingly, the conductive post 27 is electrically insulated from
the sensing portion 231.
[0082] In the embodiment shown in FIG. 7, one end of the stationary
portion 232 is disposed on the top surface 211 of the substrate 21
and the other end of the stationary portion 232 connects with the
periphery of the sensing portion 231. In some embodiments, the
second electrode 23 and the electrical insulation layer 25 are
configured to seal the first electrode 22. In some embodiments, the
second electrode 23 covered by the electrical insulation layer 25
is connected with the substrate 21 to form a first space 28. In the
embodiment of the present disclosure, the first space 28 may be a
hermetic space, which encloses the first electrode 22.
[0083] Furthermore, the first space 28 in one example is filled
with gas to serve as a sensor for detecting relative pressure, and
in another example is kept in vacuum to serve as a sensor for
measuring absolute pressure. As shown in FIG. 7, when the
air-pressure P.sub.3 of the first space 28 is smaller than the
external air-pressure P.sub.4, the sensing portion 231 and the
electrical insulation layer 25 disposed on the sensing portion 231
will deform forward the first electrode 22. If the internal
air-pressure P.sub.3 is greater than the external air-pressure
P.sub.4, the sensing portion 231 and the electrical insulation
layer 25 disposed on the sensing portion 231 will deform away from
the first electrode 22. Shortly, the deforming direction of the
sensing portion 231 of the second electrode 23 is in parallel with
the normal direction N of the substrate 21. The normal direction N
is the same as the pointing direction N.sub.1 of the first
electrode 22.
[0084] The third electrode 24 surrounds the stationary portion 232
of the second electrode 23. In the embodiment, the stationary
portion 232 includes a plurality of first protruding portions 234
while the third electrode 24 includes a plurality of second
protruding portions 241. The first protruding portions 234
outwardly radiates from the stationary portion 232, but the second
protruding portions 241 inwardly radiates toward the stationary
portion 232. Thus, the first protruding portions 234 and the second
protruding portions 241 are arranged to form an interdigital
capacitor. When the MEMS device 20 with multiple electrodes detects
air pressure, the stationary portion 232 and the third electrode 24
do not deform. Thus, the distance d.sub.3 between the first
protruding portions 234 and the second protruding portions 241 is
constant. Moreover, the first protruding portions 234 and the
second protruding portions 241 will increase the charged area of
the reference capacitor C.sub.2 so as to increase total capacitance
thereof.
[0085] FIG. 8 is a top view of a MEMS device 30 of the present
disclosure. In the embodiment shown in FIG. 8, the electrical
insulation layer 35 includes a plurality of electrical contacts
351, 352 and 353.
[0086] FIG. 9 illustrates a cross-sectional view of the MEMS device
30 taken from the line A-A' in FIG. 8. As shown in FIG. 9, the MEMS
device 30 with multiple electrodes includes a substrate 31, a first
electrode 32, a second electrode 33, a third electrode 34, an
electrical insulation layer 35 and a conductive post 37.
[0087] The first electrode 32, the second electrode 33 and the
third electrode 34 are disposed on the substrate 31. The stationary
portion 331 of the second electrode 33 is peripherally disposed
around the first electrode 32. In other words, the stationary
portion 331 of the second electrode 33 surrounds the first
electrode 32. In addition, the third electrode 34 is peripherally
disposed around the second electrode 33 and surrounds the second
electrode 33. Therefore, the third electrode 34 also surrounds the
first electrode 32.
[0088] In the embodiment shown in FIG. 9, since the first electrode
32 faces the sensing portion 332 of the second electrode 33, the
pointing direction of the first electrode 32 is in parallel with
the normal direction N of the substrate 31. Moreover, because the
stationary portion 331 faces the third electrode 34, the pointing
direction of the third electrode 34 is perpendicular to the
pointing direction of the first electrode 32. In the embodiment,
the included angle between the pointing direction of the third
electrode 34 and the pointing direction of the first electrode 32
is substantially 90.degree..
[0089] As shown in FIG. 9, the first electrode 32 is disposed on
the top surface 311 of the substrate 31. Since the stationary
portion 331 supports the sensing portion 332, the sensing portion
332 and the first electrode 32 are spaced apart by a distance
d.sub.4. The distance d.sub.4 allows the sensing portion 332 and
the first electrode 32 to form a sensing capacitor C.sub.3. When
the MEMS device 30 measures air pressure or altitude, the sensing
portion 332 will deform to change the distance d.sub.4. Since the
capacitance of the sensing capacitor C.sub.3 will changes due to
the variation of the distance d.sub.4, the sensing capacitor
C.sub.3 is a variable capacitor. When the MEMS device 30 measures
air pressure or altitude, the stationary portion 331 and the third
electrode 34 do not deform. Thus, the distance d.sub.5 between the
stationary portion 331 and the third electrode 34 does not change
due to variation of air pressure. The constant distance d.sub.5
allows the stationary portion 331 and the third electrode 34 to
form a reference capacitor C.sub.4 (also called a stationary
capacitor). In the embodiment, the electric-field direction of the
sensing capacitor C.sub.3 is substantially perpendicular to the
electric-field direction of the reference capacitor C.sub.4.
[0090] FIG. 10 illustrates a cross-sectional view of the MEMS
device 30 taken from the line B-B' of FIG. 10. As shown in FIG. 10,
the second electrode 33 includes a through hole 36. Referring to
FIG. 10, the conductive post 37 is disposed inside the through hole
36. The conductive post 37 does not contact the second electrode
33. In the embodiment, the electrical insulation layer 35 includes
a first conductive through hole 354 and a second conductive through
hole 355.
[0091] In the specification and patent scope of the present
disclosure, the term "conductive through hole" is defined as a
through hole which is filled with electrically conductive material.
Thus, the conductive through hole has characteristic of the
electrical conductor. The first conductive through hole 354
connects with the conductive post 37. Therefore, the electrical
signal may be transmitted from the electrical contact 351 to the
conductive post 37 through the first conductive through hole 354,
vice versa. In other words, the electrical signal may be
transmitted from the conductive post 37 to the electrical contact
351 through the first conductive through hole 354.
[0092] FIG. 11 illustrates a cross-sectional view of the MEMS
device 30 taken from the line C-C' of FIG. 11. In the embodiment
shown in FIG. 11, the conductive post 37 connects to the extension
terminal 321 of the first electrode 32. Thus, the electrical signal
can be transmitted to the first electrode 32 through the electrical
contact 351, the first conductive through hole 354, the conductive
post 37 and the extension terminal 321, vice versa. In other words,
the electrical signal can be transmitted from the first electrode
32 to the electrical contact 351. Since the through hole 36 and the
hole 361 keep the extension terminal 321 from connecting the
stationary portion 331 of the second electrode 33, the first
electrode 32 is electrically insulated from the second electrode
33.
[0093] In the embodiment, the second electrode 33 is electrically
coupled to the electrical contact 352 through the second conductive
through hole 355. Thus, the electrical signal is transmitted from
the electrical contact 352 to the second electrode 33 through the
second conductive through hole 355, vice versa. In other words, the
electrical signal may be transmitted from the second electrode 33
to the electrical contact 352.
[0094] FIG. 12 illustrates a cross-sectional view of the MEMS
device 30 taken from the line D-D' in FIG. 12. In the embodiment
shown in FIG. 12, the electrical contact 353 is electrically
coupled to the third electrode 34 through the third conductive
through hole 356. Thus, referring FIG. 9, individual electrical
signals can be respectively transmitted to the first electrode 32,
the second electrode 33 and the third electrode 34 through the
electrical contact 351, 352 and 353.
[0095] Moreover, in other embodiments (not shown), the second
electrode 33 may include the first protruding portions 234 shown in
FIG. 7, while the third electrode 34 may include the second
protruding portions 241 shown in FIG. 7. Thus, the first protruding
portions 234 and the second protruding portions 241 are arranged to
form an interdigital capacitor.
[0096] Referring FIG. 12, the sensing portion 332, the stationary
portion 331 and the substrate 31 define a first space 38, which is
a hermetic space enclosing the first electrode 32. However, in
other embodiment (not shown), the first space 38 may be designed to
be a non-hermetic space in accordance with other requirements.
[0097] In the embodiment shown in FIG. 12, the electrical
insulation layer 35 connects with the second electrode 33 and the
third electrode 34. Moreover, the electrical insulation layer 35,
the stationary portion 331, the third electrode 34 and the
substrate 31 define the second space 39 which is a hermetic space.
However, in other embodiments (not shown), the second space 39 may
be designed as a non-hermetic space in accordance with different
designs.
[0098] In other embodiments (not shown), the MEMS device 30 further
includes a dielectric material which is filled into the second
space 39 to increase the capacitance. In some embodiments, the
dielectric material may be selected from SiO.sub.2, Si.sub.3N.sub.4
and a mixture thereof.
[0099] FIG. 13 illustrates a modified embodiment derived from the
embodiment shown in FIG. 8. The upper portion of FIG. 13
illustrates the top view of the MEMS device 30, while the lower
portion of FIG. 13 shows the cross-sectional view of the modified
MEMS device taken from the line F-F in FIG. 13. As shown in FIG.
13, the electrical insulation layer 35 of the MEMS device 30
connects partial sensing portion 332 of the second electrode 33. In
the embodiment, through removing partial electrical insulation
layer 35 disposed on the sensing portion 332, the MEMS device 30 of
the present disclosure may reduce the residual stress of the
sensing portion 332 so as to increase the accuracy for detecting
the pressure.
[0100] FIG. 14 illustrates a modified embodiment derived from the
embodiment shown in FIG. 13. The upper portion of FIG. 14
illustrates the top view of the MEMS device 30, while the lower
portion of FIG. 14 shows the cross-sectional view of the modified
MEMS device taken from the line G-G' in FIG. 14. As shown in FIG.
14, the MEMS device 30 further includes a second conductive layer
357, which is disposed on the sensing portion 332 where the
electrical insulation layer is not disposed. The second conductive
layer 357 is then electrically coupled to the electric contact 352.
Under the electric contact 352, there is no conductive through hole
penetrating the electrical insulation layer 35. Thus, the sensing
portion 332 is electrically coupled to the electrical contact 352
through second conductive layer 357.
[0101] FIG. 15 illustrates the top view of the MEMS device 40. FIG.
16 is a cross-sectional view of the MEMS device 40 taken from the
line E-E' in FIG. 15. In the embodiment shown in FIG. 16, the MEMS
device 40 further includes a substrate 41, a first electrode 42, a
second electrode 43, a third electrode 44, an electrical insulation
layer 45 and a first conductive layer 46.
[0102] In the embodiment, the substrate 41, the first electrode 42,
the second electrode 43, the third electrode 44 and the electrical
insulation layer 45 are similar to the substrate 31, the first
electrode 32, the second electrode 33, the third electrode 34 and
the electrical insulation layer 35 shown in FIGS. 8 and 9.
[0103] In view of FIG. 16, the first conductive layer 46 is
disposed on the electrical insulation layer 45. The first
conductive layer 46 is configured to remove the excess electric
charge in the electrical insulation layer 45 so as to avoid the
interference on the sensing capacitor between the first electrode
42 and the second electrode 43. In the embodiment, the structure
and connecting relationship of the electrical contacts 451, 452,
453 are similar to those of the electrical contacts 351, 352, 353
shown in FIG. 8 and FIG. 12. As shown in FIGS. 15 and 16, the first
conductive layer 46 is electrically coupled to the electrical
contact 454 which is grounded to remove the excess electric charge
in the electrical insulation layer 45. In other words, the electric
contacts 451, 452 and 453 are electrically insulated from the first
conductive layer 46. Thus, the electrical contacts 451, 452 and 453
can be used to transmit electrical signal to the first electrode
42, the second electrode 43 and the third electrode 44,
respectively.
[0104] FIG. 17 is the top view of the MEMS device 50. FIG. 18 is a
cross-sectional view of the MEMS device 50 taken from the line H-H'
in FIG. 17. In the embodiment shown in FIG. 18, the MEMS device 50
includes the substrate 51, the first electrode 52, the second
electrode 53, the third electrode 54, the electrical insulation
layer 55, a plurality of through holes 561, 562, 563, a plurality
of conductive posts 571, 572, 573 and the integrated circuit chip
58. In order to describe the location and the connecting
relationship of the conductive posts 571, 572, 573, the conductive
post 572, 573 disposed inside the third electrode 54 may be also
called the first conductive posts 572, 573.
[0105] In the embodiment, the substrate 51 may be a glass substrate
or other dielectric substrate. The integrated circuit chip 58 is
disposed on a bottom surface of the substrate 51.
[0106] The first electrode 52 is disposed on the substrate 51 and
includes an extension terminal 521 which connects to the conductive
post 571 which is disposed inside the through hole 561. The
electrical insulation layer 55 further includes a plurality of
conductive through holes 551, 552, 553 and 554. The external
conductive trace 556 is disposed on the electrical insulation layer
55 and connects to the conductive through holes 551 and 552. The
conductive through hole 552 connects with the first conductive post
573 which is disposed inside the through hole 563. In other words,
a conductive through hole 551 in the electrical insulation layer 55
connects with the conductive post 571 and the external conductive
trace 556. Another conductive through hole 552 in the electrical
insulation layer 55 connects with the external conductive trace 556
and the first conductive post 573.
[0107] The first conductive post 573 is disposed inside the third
electrode 54 and electrically insulated from the third electrode
54. Similarly, the external conductive trace 557 is disposed on the
electrical insulation layer 55 and connects with the conductive
through holes 553 and 554. The conductive through hole 554 connects
with the first conductive post 572 which is disposed inside the
through hole 562. In other words, the first conductive post 572 is
disposed inside the third electrode 54 and electrically insulated
from the third electrode 54. FIG. 19 illustrates a cross-sectional
view of the MEMS device 50 taken from the line J-J' in FIG. 19. As
shown in FIG. 19, the conductive post 571 is disposed inside the
through hole 561. The first conductive post 572 is disposed inside
the through hole 562. The first conductive post 573 is disposed
inside the through hole 563. Thus, the conductive post 571 is
electrically insulated from the second electrode 53. The first
conductive post 572 is electrically insulated from the third
electrode 54. The first conductive post 573 is electrically
insulated from the third electrode 54.
[0108] FIG. 20 is a cross-sectional view of the MEMS device 50
taken from the line K-K in FIG. 20. As shown in FIGS. 18 and 20, an
electrical isolation layer 592 is disposed on a bottom surface 541
of the third electrode 54. The electrical isolation layer 592
further includes a plurality of conductive through holes 594 and
595. In the embodiment, the electrical isolation layer 592
surrounds the conductive through holes 594 and 595 which are
electrically insulated from the third electrode 54.
[0109] FIG. 21 is a cross-sectional view of the MEMS device 50
taken from the line L-L' in FIG. 21. As shown in FIGS. 18 and 21,
the conductive trace layers 591 and 593 are disposed below the
electrical isolation layer 592. Partial the conductive trace layers
591 and 593 are disposed between the electrical isolation layer 592
and the substrate 51. Since the conductive through hole 594
connects with the conductive trace layer 591 and the first
conductive post 573, the conductive trace layer 591 can transmit
the electrical signal to the first conductive post 573.
[0110] Similarly, since the conductive through hole 595 connects
with the conductive trace layer 593 and the first conductive post
572, the conductive trace layer 593 may transmit the electrical
signal to the first conductive post 572.
[0111] As shown in FIG. 18, the conductive through hole 594
connects with the first conductive post 573 and the conductive
trace layer 591. The integrated circuit chip 58 is disposed on the
bottom surface 511 of the substrate 51. The conductive bump 582 is
disposed on the integrated circuit chip 58. The integrated circuit
chip 58 is electrically coupled to the first conductive post 573.
In some embodiments, the bonding wire 581 connects with the
conductive trace layer 591 and the conductive bump 582. Thus, the
conductive bump 582 disposed on the integrated circuit chip 58 is
electrically coupled to the conductive trace layer 591 through the
conductive wire 581 so as to be electrically coupled to the first
conductive post 573. Therefore, the first electrical signal from
the integrated circuit chip 58 is transmitted to the first
electrode 52 through the conductive bump 582, the conductive wire
581, the conductive trace layer 591, the conductive through hole
594 in the electrical isolation layer 592, the first conductive
post 573, the conductive through hole 552 in the electric
insulation layer 55, the external conductive trace 556, the
conductive through hole 551 in the electric insulation layer 55,
the conductive post 571, the extension terminal 521, vice versa. In
other words, the first electrical signal is transmitted from the
first electrode 52 to the conductive bump 582.
[0112] As shown in FIG. 18, the second electrode 53 is connected to
the conductive through hole 553. The external conductive trace 557
is connected with the conductive through holes 553 and 554. Thus,
the second electrode 53 is electrically coupled to the first
conductive post 572. The first conductive post 572 is electrically
coupled to the conductive trace layer 593 through the conductive
through hole 595. The conductive trace layer 593 and the conductive
bump 583 is connected through the conductive wire 584. In some
embodiments, the second electrical signal of the integrated circuit
chip 58 can be transmitted from the conductive bump 583 to the
second electrode 53 through the conductive wire 584, the conductive
trace layer 593, the conductive through hole 595, the first
conductive post 572, the conductive through hole 554, the external
conductive trace 557, the conductive through hole 553, vice versa.
In other words, the second electrical signal can be transmitted
form the second electrode 53 to the conductive bump 583. In the
embodiment, since the first electrical signal path is electrically
insulated form the second electric signal path, the first
electrical signal won't be transmitted to the second electrode,
vice versa.
[0113] FIG. 22 is a cross-sectional view along with the
cross-sectional line I-I' of FIG. 22. In the embodiment shown in
FIGS. 18 and 22, since the third electrode 54 connects with the
conductive through hole 597 in the electrical isolation layer 592,
the third electrode 54 is electrically coupled to the conductive
trace layer 596. The conductive trace layer 596 and the conductive
bump 585 is electrically coupled through the conductive wire 586.
In some embodiments, the third electrical signal of the integrated
circuit chip 58 may be transmitted from the conductive bump 585 to
the third electrode 54 through the conductive wire 586, the
conductive trace layer 596, the conductive through hole 597, vice
versa. In other words, the third electrical signal could be
transmitted from the third electrode 54 to the conductive bump 585.
In the embodiment, since the third electrical signal path is
electrically insulated form the first electrical signal path or the
second electrical signal path, the third electrical signal won't be
transmitted to the first electrode or the second electrode,
respectively.
[0114] In summary, the first conductive post 573 is disposed inside
the third electrode 54 and electrically insulated from the third
electrode 54. The external conductive trace 556 is disposed on the
electric insulation layer 55 which includes conductive through
holes 551 and 552. The electrical isolation layer 592 is disposed
on the bottom surface 541 of the third electrode 54 and includes
another conductive through hole 594. Furthermore, the conductive
trace layers 591 and 593 are disposed below the electrical
isolation layer 592. Partial conductive trace layers 591 and 593
are disposed between the electrical isolation layer 592 and the
substrate 51. The conductive bump 582 is disposed on the integrated
circuit chip 58. In order to allow the integrated circuit chip 58
to be electrically coupled to the conductive post 571 and the first
electrode 52, the connecting relations are built as followings: A
conductive through hole 551 in the electrical insulation layer 55
connects with the conductive post 571 and the external conductive
trace 556. Another conductive through hole 552 in the electrical
insulation layer 55 connects the external conductive trace 556 and
the first conductive post 573. The conductive through hole 594 in
the electrical isolation layer 592 connects with the first
conductive post 573 and the conductive trace layer 591. The
conducting wire 581 connects with the conductive trace layer 591
and the conductive bump 582.
[0115] FIG. 23 illustrates a modified embodiment of the MEMS device
50. The upper drawing of FIG. 23 illustrates the top view of the
MEMS device 60, while the lower drawing of FIG. 23 shows the
cross-sectional view of the MEMS device 60 taken from the line M-M'
in FIG. 23. As shown in FIG. 23, the MEMS device 60 includes a
substrate 61, a first electrode 62, a second electrode 63, a third
electrode 64, an electric insulation layer 65, a first conductive
layer 66 and an integrated circuit chip 67. The first conductive
layer 66 is disposed on the electric insulation layer 65 and
configured to remove the excess electric charge in the electrical
insulation layer 65 so as to avoid the interference on the sensing
capacitor between the first electrode 62 and the second electrode
63 due to the accumulated charge.
[0116] As shown in FIG. 23, the first conductive layer 66 is
connected to the electric contact 654 which is grounded to remove
the excess electric charge in the electrical insulation layer 65.
The external conductive traces 651 and 652 and the electric contact
653 are electrically insulated from the first conductive layer 66.
Since the external conductive traces 651 and 652 and the electric
contact 653 can transmit electrical signals to the first electrode
62, the second electrode 63 and the third electrode 64,
respectively. Thus, the integrated circuit chip 67 can respectively
transmit electrical signals to the first electrode 62, the second
electrode 63 and the third electrode 64 through the external
conductive traces 651, 652 and the electric contact 653.
[0117] FIG. 24 shows an embodiment of a MEMS device 70. The upper
drawing of FIG. 24 illustrates the top view of the MEMS device 70,
while the lower drawing of FIG. 24 shows the cross-sectional view
of the MEMS device 70 taken from the line N-N' in FIG. 24. In the
embodiment, the substrate of MEMS device 70 is an integrated
circuit chip 71. As shown in FIG. 24, the MEMS device 70 includes
the integrated circuit chip 71, a first electrode 72, a second
electrode 73, a third electrode 74, an electrical insulation layer
75, a conductive layer 76 and a plurality of conductive posts 771
and 772. In order to describe the locations and the connecting
relationship of the conductive posts 771 and 772, the conductive
post 771 disposed inside the third electrode 74 is called a second
conductive post 771.
[0118] The integrated circuit chip 71 further includes at least one
conductive through holes 712, 713, 714 and 715 and at least one
conductive bumps 716, 717, 718 and 719.
[0119] In the embodiment, the conductive bumps 716, 717, 718 and
719 are connected with t the conductive through holes 712, 713, 714
and 715, respectively. The conductive through holes 712, 713, 714,
715 are connected with the bonding layer 78, respectively. The
conductive through holes 713, 714 and 715 are electrically coupled
to the second electrode 73, the first electrode 72 and the third
electrode 74 through the binding layer 78 respectively. In other
words, the electrical signals of the conductive bumps 717, 718 and
719 are transmitted to the second electrode 73, the first electrode
72 and the third electrode 74 through the conductive through holes
713, 714 and 715 and the bonding layer 78 respectively.
[0120] As shown in FIG. 24, the conductive layer 76 is disposed on
the electrical insulation layer 75 and configured to remove the
accumulated electric charge in the electrical insulation layer 75
so as to avoid the interference on the sensing capacitor between
the first electrode 72 and the second electrode 73.
[0121] In the embodiment, the second conductive post 771 is
disposed inside the third electrode 74 and electrically insulated
from the third electrode 74. The conductive bump 716 is
electrically coupled to the second conductive post 771 through the
conductive through hole 712 and the bonding layer 78. The second
conductive post 771 is electrically coupled to the conductive layer
76 through the electrical contact 791. If the conductive bump 716
is grounded, the accumulated electric charge in the electrical
insulation layer 75 can be removed.
[0122] FIG. 25 illustrates an embodiment of a MEMS device 80. The
upper drawing of FIG. 25 illustrates the top view of the MEMS
device 80, while the lower drawing of FIG. 25 shows the
cross-sectional view of the MEMS device 80 taken from the line O-O'
in FIG. 25. As shown in FIG. 25, the MEMS device 80 includes a
substrate 81, a first electrode 82, a second electrode 83, a third
electrode 84, an electric insulation layer 85, and the conductive
post 86. The substrate 81 includes at least one openings 811, 812
and a back chamber 813. In the embodiment, the electrical
insulation layer 85, the third electrode 84, the stationary portion
831 of the second electrode 83 and the substrate 81 define a second
space 87. In the embodiment shown in FIG. 25, the at least one
openings 811 and 812 communicate with the second space 87. In other
words, the second space 87 of the embodiment is not a hermetic
space.
[0123] In the embodiment, the back chamber 813 is disposed in the
substrate 81 under the first electrode 82. In the embodiment, the
second electrode 83, the substrate 81, the first electrode 82 and
the electrical insulation layer 85 define a first space 88. The
first electrode 82 further includes a plurality of apertures 821 by
which the first space 88 can communicate with the back chamber 813.
In other word, since the first space 88 can communicate with the
back chamber 813 by apertures 821, the first space 88 is not a
hermetic space. Thus, the MEMS device 80 of the present embodiment
utilizes the back chamber 813, the apertures 821 and openings 811
and 812 to form a MEMS microphone.
[0124] In addition, since the distance d.sub.6 between the
stationary portion 831 and the third electrode 84 is not affected
by sound wave, the stationary portion 831 and the third electrode
84 can form a reference capacitor. Therefore, the MEMS microphone
of the present disclosure utilizes the differential design to
reduce the noise.
[0125] In the embodiment shown in FIG. 26, a MEMS device 90 can be
applied for Si-interposer 98. In 3-dimensional integrated circuit
(3D-IC), Si-interposer 98 is disposed between the integrated
circuit chip 99 and the substrate 97. For 3D-IC, the power
integrity plays an important role in 3D-IC. In order to provide
clean power, decouple capacitor is disposed close to the integrated
circuit chip 99. The MEMS device of the present disclosure has
multiple capacitors which is capable of providing decoupling
function.
[0126] In the embodiment shown in FIG. 26, a MEMS device 90 of the
present disclosure includes a first electrode 91, a second
electrode 92 and a third electrode 93. The pointing direction
(N.sub.4) of the first electrode 91 is in parallel with the normal
direction (N.sub.3) of the Si-interposer 98. The pointing direction
(N.sub.5) of the third electrode 93 is perpendicular to the
pointing direction (N.sub.4) of the first electrode 91. The space
between the first electrode 91 and the second electrode 92 may be
filled with dielectric material 94. The dielectric material 94 can
be oxide or nitride such as SiO.sub.2 or Si.sub.3N.sub.4. Thus, the
first electrode 91 and the second electrode 92 may form a first
decoupling capacitor. In addition, the space between the second
electrode 92 and the third electrode 93 may be filled with
dielectric material 95. The dielectric material 95 can be oxide or
nitride such as SiO.sub.2 or Si.sub.3N.sub.4. Therefore, the second
electrode 92 and the third electrode 93 may form a second
decoupling capacitor. Furthermore, since the MEMS device 90 is
disposed in the Si-interposer 98, the MEMS device 90 is surrounded
by silicon.
[0127] The embodiment shown in FIG. 27 is a modified embodiment
derived from the embodiment shown in FIG. 26. In the embodiment,
the third electrode 93-1 further includes a plurality of second
protruding portions 931. The second electrode 92-1 further includes
a plurality of first protruding portions 921. The first protruding
portions 921 and the second protruding portions 931 are arranged to
form an interdigital capacitor. Because the second electrode 92-1
and the third electrode 93-1 do not deform, the distance between
the first protruding portions 921 and the second protruding
portions 931 is constant.
[0128] FIG. 28 illustrates a flow chart of fabricating method for a
MEMS device. As shown in FIG. 28, the fabricating method includes
following steps. The step 1010 provides a Silicon On Insulator
(SOI) wafer which includes a device layer, an electrical insulation
layer and a handle layer. The step 1020 etches the device layer to
form recession and a plurality of slots exposing the electrical
insulation layer. The step 1030 provides a substrate wafer and
places a first electrode on the substrate wafer. The step 1040
bonds the substrate wafer and SOI wafer through wafer-to-wafer
bonding process. Finally, the step 1050 removes the handle layer.
The number of the step does not necessary mean the order of each
steps.
[0129] The flow chart shown in FIG. 28 can be illustrated in
following description relating to FIGS. 29 to 33.
[0130] In the step 1010, a SOI wafer 101 is provided as shown in
FIG. 29. The SOI wafer 101 includes a device layer 102, an
electrical insulation layer 103 (made of SiO.sub.2 in the
embodiment) and a handle layer 104. Furthermore, the electrical
insulation layer 103 is disposed between the device layer 102 and
the handle layer 104.
[0131] In the step 1020, the device layer 102 is etched to form
recession 301 as shown in FIG. 30. In this step, the etching
process is a wet etching (KOH etching).
[0132] In the step 1020, the device layer 102 having the recession
is etched to form a plurality of slots 302, 303 and 304 which
expose the electrical insulation layer 103 as shown in FIG. 31.
These slots 302, 303 and 304 and the recession 301 define the
second electrode 401 and the third electrode 402 in the device
layer 102. The second electrode 401 includes a sensing portion 404
and a stationary portion 403. In this step, the etching process is
a dry etching such as Deep Reactive Ion Etching (Deep RIE).
[0133] As shown in FIG. 31, the slot 302 is configured for the
stationary portion 403 to form a plurality of first protruding
portions 234 shown in FIG. 7 and for the third electrode 402 to
form a plurality of second protruding portions 241 shown in FIG. 7.
In addition, the first protruding portions 234 and the second
protruding portions 241 are arranged to form an interdigital
capacitor.
[0134] In the embodiment, the etching step 1020 for the device
layer 102 further includes a step of etching the stationary portion
403 to form a slot 303 exposing the electrical insulation layer
103. The slot 303 will form a through hole and the conductive post
406. The conductive post 406 is disposed inside the slot 303. Thus,
the conductive post 406 is electrically insulated from the
stationary portion 403.
[0135] In the step 1030, the substrate wafer 501 is provided as
shown in FIG. 32 and the first electrode 405 is disposed on the
substrate wafer 501.
[0136] In the step 1040, the SOI wafer 101 and the substrate wafer
501 is bonded through wafer-to-wafer bonding process. This step
allows the second electrode 401 and the third electrode 402 to be
bonded on the top surface 502 of the substrate wafer 501. In this
step, a wafer-to-wafer anodic bonding process is implemented. In
the embodiment, the stationary portion 404 faces the first
electrode 405, while the stationary portion 403 faces the third
electrode 402. In addition, included angle between the pointing
direction N.sub.2 of the third electrode 402 and the pointing
direction N.sub.1 of the first electrode 405 is substantial
90.degree..
[0137] As shown in FIG. 33, one end of the stationary portion 403
is disposed on the top surface 502 of the substrate 501 and the
other end of the stationary portion 403 is connected with the
periphery of the sensing portion. The second electrode 401 is
configured to seal the first electrode 405. In some embodiments,
the sensing portion 404 of the second electrode 401, the stationary
portion 403, the electrical insulation layer 103 and the substrate
501 define the first space 601. In the embodiment, the first space
601 is a hermetic space, which encloses the first electrode
405.
[0138] In the step 1050, the handle layer 103 shown in FIG. 33 is
removed to complete the MEMS device shown in FIG. 34. In this step,
the etching process is a wet etching such as KOH etching.
[0139] As shown in FIG. 34, the electrical insulation layer 103
covers the second electrode 401 and the third electrode 402. In
addition, the electrical insulation 103, the stationary portion
403, the third electrode 402 and the substrate 501 define the
second space 602. In the embodiment, the second space 602 is a
hermetic space.
[0140] In addition, the fabricating method for the MEMS device
shown in FIG. 28 may further include one of the following steps or
a combination thereof so as to form the structures shown in FIGS.
35 to 37.
[0141] In the step 1060, the electrical insulation layer 103 may be
further etched to form at least one openings 701, 702 and 703 as
shown in FIG. 35. In this step, the etching process is a dry
etching such as Reactive Ion Etching (RIE).
[0142] In the step 1070, the first conductive layer 801 is
deposited on the electrical insulation layer 103 and is deposited
in the openings 701, 702 and 703 as shown in FIG. 36. In this step,
the depositing process is a metal depositing process such as metal
deposition-aluminium process.
[0143] In the step 1080, the deposited conductive layer 802 is
deposited on the first conductive layer 801 to form at least one
electrical contacts 901, 902 and 903. The electrical contacts 901,
902 and 903 are electrically coupled to the first electrode 405,
the second electrode 401 and the third electrode 402, respectively.
In this step, the depositing process is a metal depositing process
such as metal deposition-aluminium process.
[0144] Although the present disclosure and its advantages have been
described in detail, it should be understood that various changes,
substitutions and alterations can be made herein without departing
from the spirit and scope of the disclosure as defined by the
appended claims. For example, many of the processes discussed above
can be implemented in different methodologies and replaced by other
processes, or a combination thereof.
[0145] Moreover, the scope of the present application is not
intended to be limited to the particular embodiments of the
process, machine, manufacture, and composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present disclosure, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed, that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present disclosure. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps.
* * * * *